Wendelstein 7-X is an advanced stellarator. When finished in 2010 it will be used to contain plasma up to 100 million degrees in a very powerful magnetic field. It's one step towards building a nuclear fusion reactor. I was surprised to find out just now that there are already plans to build one in France.posted by namagomi (30 comments total)

Yeah, but it's really a ripoff by the manufacturers, since with a little soldering work you can overclock that baby to push 110 million.posted by XQUZYPHYR at 5:29 PM on May 1, 2006

Fool! Your powers are nothing compared to the might of my Wendelstein 7-X!! (laughs manically)posted by bitmage at 5:47 PM on May 1, 2006

This is also the first step towards bulding a lightsaberposted by subaruwrx at 5:49 PM on May 1, 2006

Wow, the structure is really beautiful, very sculptural. I'm with loquacious on this one, there's nothing hotter (HA!) than sexy science.posted by lekvar at 6:00 PM on May 1, 2006

I'm a little confused -- has a controlled fusion reaction ever been achieved on a smaller scale, or is the point of building this reactor to see if they can create one at all?posted by stemlot at 6:07 PM on May 1, 2006

I'm a little confused -- has a controlled fusion reaction ever been achieved on a smaller scale, or is the point of building this reactor to see if they can create one at all?

Well, you can't do it without the proper equipment, and once they get the proper equipment, then they can try it. We know fusion will work if things get hot enough, the problem is just making things hot enough.posted by delmoi at 6:14 PM on May 1, 2006

I regret to say that I have nothing to do with this.posted by wendell at 6:46 PM on May 1, 2006

Stemlot, check out that wikipedia article. Thems good readings.

As I understand the it, there are several operating fusion reactors in existence today, but they nearly all require more energy to induce a reaction than they produce, and the reactions don't last very long at all.

That is to say, it is definitely possible to make a fusion reaction happen (and it has happened), but not possible to use it as feasible power source. The point of building this reactor is to experiment with the stellerator design, with the ultimate goal of producing self sustainable fusion (a reactor that makes more power than it consumes, and that will work for as long as is required).posted by Drunken_munky at 6:49 PM on May 1, 2006

Looking at the photograph "Fabrication of Coils": Do they just have an entire I-beam heated to red hot and being bent? Bender Bending Rodriguez, man.posted by TheOnlyCoolTim at 7:04 PM on May 1, 2006

Do they just have an entire I-beam heated to red hot and being bent?

doubtful - site says the coils are supposed to be superconducting. they're probably made of NbTi, but most certainly not just bent steel beams. it actually looks kind of like a big rectangular tube to me - i suspect what you're seeing is probably a cryostat that keeps the coils immersed in liquid helium so that they superconduct.

but i am not a plasma physicist nor involved with this project, and there's a lack of technical detail on that page (bizzare, for what must be such a big project) so i'm really not sure.posted by sergeant sandwich at 7:20 PM on May 1, 2006

The reactor being built in France (ITER) is a tokamak, not a stellarator.posted by atrazine at 7:25 PM on May 1, 2006

there are several operating fusion reactors in existence today, but they nearly all require more energy to induce a reaction than they produce

No existing reactor has produced more energy than was being input. ITER is expected to produce about 10 times more power than is used to hear the plasma, which due to inefficiencies means that the total power produced is about equal to the total power input.posted by pombe at 7:37 PM on May 1, 2006

delmoi:Has our understanding of physics changed at all since 50 years ago when we said fusion reactors would be ready in 50 years?

Our understanding of physics has changed so much that books on astrophysics or cosmology that are 5 years old are badly out of date, and ones that are over 25 are all but useless.

However, I tend to think that practical fusion is more of an engineering problem, not a physics problem. Although it's still possible that some kind of low-scale fusion will show up (something like muon-catalyzed fusion or bubble fusion, but energetically productive.)posted by Mitrovarr at 1:26 AM on May 2, 2006

I saw a documentray on this the other night, and the issue is scale - they feel if they can build bigger reactors, they will get closer and closer to a longer, sustaining reaction that produces more energy than put in.posted by Jimbob at 2:49 AM on May 2, 2006

Our understanding of physics has changed so much that books on astrophysics or cosmology that are 5 years old are badly out of date, and ones that are over 25 are all but useless.

However, I tend to think that practical fusion is more of an engineering problem, not a physics problem. Although it's still possible that some kind of low-scale fusion will show up (something like muon-catalyzed fusion or bubble fusion, but energetically productive.)

Just to harp on this a little bit. I watched the Con Edison Distinguished Lecture Series at Columbia University, and Prof. Jerry Navratil stood up and delivered an hour speech talking about the hopes for the ITER project.

One really impressive graph showed the output Q as a trend over the years. There's a nice steady increase towards 1 (sustained nuclear fusion reaction with more energy being produced that being put in) starting from the 1960s, with 1 coming within the next couple years, and 10 feasible in the distance future. Understanding plasma and the required containment fields is very difficult, but a lot of progress has been made in the last 5 years alone.

Prof. Navratil seems pretty confident, so I'll go with him on this (he's a great Electrodynamics professor too!)posted by onalark at 5:06 AM on May 2, 2006

I tend to think that practical fusion is more of an engineering problem, not a physics problem

Good description of the problem. Hot fusion -- like stars and nuclear weapons -- is a difficult problem. The easiest fusion reaction demand lots of pressure, which means lots of heat, and produce lots of neutrons. Lots of heat and lots of neutrons are hard on things like containment systems and plant operators.posted by eriko at 5:28 AM on May 2, 2006

I'm just looking forward to all the helium produced by fusion. A new golden age of the blimp will be upon us!posted by Astro Zombie at 5:48 AM on May 2, 2006

Haven't these guys seen Spiderman II?????posted by pmbuko at 6:53 AM on May 2, 2006

I'll admit that I don't know the first thing about the physics of heat and plasma and so on. But what's preventing a source of heat that is 100 million degrees melting the metal that's just one metre away from it?

Heat and temperature are different things. Heat is a form of energy; temperature is a measure of the quality of heat energy. Given two identical chunks of matter, the one with the higher temperature will certainly have more heat energy; but if you dump a cup of hot coffee into a bathtub full of cold water, the bath's temperature will rise scarcely at all even though it now contains all the heat energy from the coffee on top of what it had before.

If you're trying to melt metal, you need to pump enough energy into it to raise its temperature above its melting point. If the metal object in question is large, and has a high melting point, that's hard.

Imagine holding a saucepan of water above a cigarette lighter. The flame is pretty damn hot - it's certainly above the melting point of aluminium - but it's going to take you more butane than you have in your lighter to boil away the water, much less melt out the bottom of the saucepan.

In a fusion reactor, you're clearly dealing with much higher temperatures than you get in a butane lighter flame; but you've also got a much bigger metal object to heat than a saucepan, and the plasma "flame" is absolutely not allowed to touch the metal containment. If it did, the containment would instantly suck so much heat energy out of the gas-like plasma "flame" as to "put it out".

When a fusion reactor is running, the plasma will glow - that is, convert some of its heat energy to electromagnetic radiation: light. The plasma will literally shine like a little star. Conversion to radiation is the only way the plasma's heat energy can leave the plasma.

Light doesn't actually have a temperature, as such. Only matter has temperature; radiation has intensity and wavelength. We often talk of infrared light as "radiated heat" but that's really just verbal shorthand. What you feel when you stand in front of a bar radiator is not the temperature of the glowing bar - try touching it, if you want to feel that! - but a temperature rise in your own skin, caused by your skin's partial absorption of the light (visible and infrared) light emitted by the bar.

A fusion reactor's containment vessel is reflective inside, so it won't absorb much of the energy radiated by the plasma; it will reflect most of it back in to keep the plasma cooking. The containment is designed to absorb only enough radiation to generate steam to run a turbine. It's not even going to get close to melting temperature.posted by flabdablet at 9:05 AM on May 2, 2006

You think you’re better than the Wendelstein 7-X?
Wendelstein!
Wendelstein!
Wendelstein!posted by Smedleyman at 1:17 PM on May 2, 2006

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